Why are communities beginning to look at wastewater as a potential drinking water source?

Dangerous Contaminants

The
biggest reason is because many metropolitan areas are outgrowing their
water supply, and unless they are able to come up with additional sources or
significantly conserve the water they currently have access to, there will be problems ahead.

U.S.
scientists have warned that parts of the country will soon need to find
new sources of drinking water. The United Nations calls thirst a growing
global crisis. Desalination, while it works, remains too expensive to
be practical for most areas. Reclaimed wastewater has long been returned
to the environment or used for irrigation. In the Southwest, where water
has always been scarce, elaborate systems are already in place to reclaim
wastewater. The master-planned community of Anthem, at the edge of Phoenix,
uses treated wastewater to irrigate two golf courses and acres upon acres
of parks. But drinking water for the roughly 25,000 residents still comes
from the Colorado River.

And
as an example of the rising costs of water and all its attendant schemes,
Anthem residents are currently facing up to a 50 percent increase in water
rates this year and more in coming years to pay for the reclamation facility.
Residents are up in arms over the unexpected rate hike and what they see
as a lack of disclosure on the part of the builder and the local water
company about the plant's true costs. Already drinking it elsewhere, treated
wastewater is already finding its way into water glasses. Recycled water
flows into a stream that feeds Virginia's Occoquan Reservoir, Kemsley
notes. "In Los Angeles, treated wastewater is added to the Montebello
Forebay, where it percolates through the soil to replenish the groundwater
supply.

Also
in California, the Orange County Water District’s (OCWD’s) Water Factory
21 facility reclaims wastewater that is then injected into aquifers to
provide a pressurized barrier against seawater intrusion into groundwater."
Earlier this month, California approved operation of the Advanced Water
Purification Facility (AWPF), the largest water reclamation plant in the
nation. It will produce 70 million gallons a day of drinkable water from
sewage — supplying about 10 percent of the water needed for the district's
2.3 million residents.

Kemsley
explains how the facility reduces levels of organic chemicals, pathogens
and pharmaceuticals:

Big stuff like tree limbs are removed.

Coffee
grounds and other granulars settle out.

Chemicals are added to encourage
gunk to clump and settle out.

Bacteria are added to break down poo.
Now it's ready for discharge into the ocean.

To make it drinkable:

Sodium
hypochlorite is added to disinfect the water, which then goes through
microfilters.

The water is treated with reverse osmosis, a process used
in some home-water filters, to remove dissolved contaminants.

Finally,
hydrogen peroxide is added and the water is irradiated with ultraviolet
light to removed the last of the organics. The water is as clean as and
probably cleaner than standard tap water, said Mehul Patel, OCWD’s principal
process engineer. The Environmental Protection Agency is seeing greater
interest in using treated wastewater to recharge aquifers, the article
states. "As water supplies tighten, perhaps more communities will be asked
to put their faith in chemistry and accept recycled water into their drinking
supply," Kemsley writes.

Finally,
one alternative is for large metro areas to begin to recycle some of their
wastewater, just as in California, to make it suitable for drinking or
at least suitable for non-potable industrial uses. Reducing industrial
uses of potable water will help many rapidly growing areas meet their
drinking water needs in the future.